Air-cooled electric outboard motor

ABSTRACT

An air-cooled electric outboard motor includes a power unit having air intake and exhaust ports shielded from the weather by being provided in a bottom wall of a housing for the power unit. An electric motor having a cylindrical housing is mounted vertically in the housing. The motor includes an output shaft passing through the bottom of the power unit for driving a propeller type lower drive unit. The motor has top and bottom end bell housings with radially facing inflow and outflow orifices respectively and a centrifugal fan is mounted on the output shaft radially within the bottom bell housing. Baffle plates extend upward from the bottom of the housing between the intake and exhaust ports. Speed control components are mounted on the baffle plates and the plates are so positioned to direct air entering the intake ports to flow upward over the speed control components. A directive shroud around the bottom end bell causes the outflow orifices of the motor to communicate with the exhaust ports, while the inflow orifices are in communication with the intake ports by means of the enclosed interior of the power unit housing. The fan drives the dual pass circulating air flow within the power unit, first passing upward over the speed control components and then downward through the motor.

United States Patent 11 1 Ray 1 Apr. 22, 1975 AlR-COOLED ELECTRICOUTBOARD MOTOR [76] Inventor: Morton Ray, 3801 Moss Dr..

[52] U.S.Cl. 115/18 E; 310/62 [51] Int. Cl. B63h 1/04 [58] Field ofSearch 115/17, 18 E, 18 R, 34 R; 310/59. 58. 56, S7, 62

[56] References Cited UNITED STATES PATENTS 2336774 5/1960 Holley et al.310/62 X 3.013.518 12/1961 Smith ll5/l8E 3.553.505 1/1971 Sato 310/68 D3.575.524 4/1971 Adajian 310/62 Primary Etaminer-Trygve M. BlixAssistant E.\'aminerGregory W. OConnor [57] ABSTRACT An air-cooledelectric outboard motor includes a power unit having air intake andexhaust ports shielded from the weather by being provided in a bottomwall of a housing for the power unit. An electric motor having acylindrical housing is mounted verti' cally in the housing. The motorincludes an output shaft passing through the bottom of the power unitfor driving a propeller type lower drive unit. The motor has top andbottom end bell housings with radially facing inflow and outfloworifices respectively and a centrifugal fan is mounted on the outputshaft radially within the bottom bell housing. Baffle plates extendupward from the bottom of the housing between the intake and exhaustports, Speed control components are mounted on the baffle plates and theplates are so positioned to direct air entering the intake ports to flowupward over the speed control components. A directive shroud around thebottom end bell causes the outflow orifices of the motor to communicatewith the exhaust ports, while the inflow orifices are in communicationwith the intake ports by means of the enclosed interior of the powerunit housing. The fan drives the dual pass circulating air flow withinthe power unit, first passing upward over the speed control componentsand then downward through the motor.

7 Claims, 7 Drawing Figures PATENTEU APR 2 2 I975 SHEET 1 Bf 3 kF/GTZAIR-COOLED ELECTRIC OUTBOARD MOTOR FIELD OF THE INVENTION This inventionrelates generally to electric outboard motors. and more particularly. tothe dual pass air cooling of the power unit of such an outboard motorvia air intake and exhaust ports in a bottom wall of the power unithousing.

BACKGROUND OF THE INVENTION Heretofore. convection cooled electricoutboard motors. have been used on small boats. primarily-as auxiliarymotors for low power. low speed. relatively silent operationapplications. such as for trolling. Generally. an internal combustionoutboard motor has provided the motive power for high speed. Whileelectric motors provide various advantages over internal combustionengines. such as the ability to electrically reverse rotation andcontrol speed. obviating the need for expensive mechanical moving partsin the motor and complicated mechanical transmissions. the eliminationof sources of water and noise pollution. minimal maintenance and runningexpense. relatively high power electric outboards have not generallybeen used.

It is believed that this lack of use is primarily due to the fact thatthere is no available. inexpensive and reliable technique of intenselycooling an electric outboard motor to obtain high power performancefront a motor of small dimensions and relatively light weight.

Basically. the prior art in electric outboard motor construction has notsolved the problem of integrating a motor/fan combination within anelectric outboard motor housing in a manner which is reliable in theharsh marine environment. The cooling capacity required for largeelectric motors has not previously been attained. in so far as I amaware. Problems have also arisen concerning the intake of debris.foreign matter. precipitation. water spray and corrosive materials alongwith the cooling air.

Furthermore. there is a need in large motors to pro title for thecooling of ancillary components of an electric outboard motor. such assolid state speed control devices.

OBJECTS OF THE INVENTION Thus. it is an object of the present inventionto provide a new and improved air cooled electric outboard motor with adual pass air flow and having air intake and exhaust ports located to beshielded from the weather and from the intake of debris.

It is a further object of the present invention to provide a new andimproved air-cooled electric outboard motor utilizing a commerciallyavailable electric motor/fan combination.

It is another object of the present invention to pro vide a new andimproved air cooled electric motor with means for cooling ancillaryelectric circuitry.

SUMMARY OF THE INVENTION In the present invention. an air-cooledelectric outboard motor is provided having air intake and exhaust portson the underside of the power unit housing so as to be shielded from theweather. Baffle means extend upward from the housing base between theintake and exhaust ports. A standard d.c. electric motor is verticallydisposed in the housing in an inner chamber defined within the bafflemeans with a fan driven by the (ill output shaft located in the lowerend bell housing. The fan sets up a circulation of air within thehousing in which air is drawn through the intake ports upward into avertically elongated outer chamber or channel defined between the bafflemeans and the housing. over the top of the baffle means and down throughthe motor and out the exhaust ports. The outer chamber provides spacefor mounting ancillary components. such as solidstate speed controldevices and relays in the intake air stream to allow for cooling thedevices. The baflIe means. normally plates. serve the dual pur pose ofdirecting the air flow over the ancillary components and providing astructure on which to mount these components.

Other objects and features of the present invention will become apparentupon a perusal of the following detailed description of a preferredembodiment taken in conjunction with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a side view of the electricoutboard motor assembly of the present invention with a portion of thepower unit housing broken away to espose the parts therein:

FIGv 2 is an exploded isometric side view illustrating the assembly ofthe power unit;

FIG. 3 is an elevation view of a motor/fan combination within the powerunit:

FIG. 3A is a partial cross-section view of FIG. 3 showing thecentrifugal fan;

FIG. 4 is a crosssectional side view of a base for the power unit;

FIG 5 is a cross-sectional side view of the power unit illustrating thedual pass flow of cooling air. and

FIG. 6 is a partial horizontal cross-sectional \iew along the lines h-6of FIG. 5.

DETAILED DESCRIPTION OF THE DRAWING Referring to FIG. I. the electricoutboard motor assembly III of the present invention includes a powerunit I2 containing a vertically oriented air-cooled electric motor [4having a downwardly directed output shaft [6 passing through base [5.The shaft 16 drivingly engages the drive means of lower drive unit [8directly below the power unit. The drive unit 18 serves to rotatepropeller I) in response to rotation of the motor output shaft 16 in anobvious manner. The motor is fed from an external electric storagebattery 20. such as a cow ventional lead-acid battery. via speed controlcircuitry 2|. preferably mounted in power unit 12 so as to be aircooledand responsive to a manual control grip 22 on the tiller arm or handle25 on the outside of the power unitv Outboard motor assembly [0 furthercomprises a conventional mounting 23 for attaching the lower drive unit18 to the transom of a boat including a C clamp type device 24. Thetiller arm 25 extends horizontally from the power unit base [5 toprovide the means for manually rotating the motor assembly 10 about agenerally vertical axis in mounting 23 for steering purposes. Controlgrip 22 is conveniently mounted at the end of tiller arm 25 and operatesa potentiometer within enlarged portion 25a of the arm for controllingon-off operation and the speed of the motor assembly 10 in aconventional manner. Control grip 22 may utilize an integral shaft and arotary switch (not shown) to control the on-off operation and forreversing the direction of the motor via suitable contactors.

Power unit l2 comprises a housing formed of a cover 26 fitting over thebase IS; the cover 26 and base I preferably having a streamlined ovalcross'section. A handle 28. which extends upwardly from the top of cover26, is used for tilting the outboard unit out of the water in aconventional manner.

The base I5. as best shown in FIGS. 2 and 4 is prefer ably a castaluminum part. having a bottom oval wall 30. smoothly merging into anupwardly directed sidewall 32 around the periphery ofthe oval shape. Thetop of the periphery. of sidewall 32 has a step 34 including ahorizontal shoulder 36 providing a seat for the cover 26. A tubularshank 38 extends downwardly from a hole 39 in the center of bottom wall30. Shank 38 is received by the lower unit 18 with the shaft I6extending from motor [4 through opening 39 (see FIGS. 2 and 5 I.

For advantageously shielding the air-cooling system front the intake andblowing of debris and precipita lion. air intake and exhaust ports orapertures 40 and 42. respectively. are both prmided in the bottom wallof base [5. This assures that the air both being sucked in and blown outis shielded from above by the power unit I2 itself. Falling debris orprecipitation is thus not susceptable to being in interference with theimportant cooling function. An additional advantage lies in that thenoise level is reduced with respect to the occupants of the boat sincethe ports and 42 are all directed downwardly.

Air exhaust ports 40 tsee FIG. 2) are configured as a plurality ofpreferably equi-angularly spaced sector shaped apertures surrounding thehole 39. In view of the streamlined oval shape of base 30. air intakeports 42 are preferably provided in a pair of separate sets. generallydesignated by reference numeral sets. 42a and 42". at the front and rearof the base 30. In accor dance with the broader aspects of theinvention. the sets of ports 40 and 42 could be arranged concentricallyin the base l5 where the cylindrical rather than the streamlined powerunit configuration is preferred Screens 44a and 44h may be respectivelyprovided over the air intake ports 42 for further assuring against theintake of debris.

For cutting off direct communication between air in take ports 42 andexhaust ports 40. the base 15 is provided with a pair of webs 46a and46h upstanding from the bottom wall 30 and extending between oppositesidewalls 32. Webs 46a and 46/) respectively separate the aperture sets42a and 42h from the ports 40. As will further be understood as thediscussion proceeds. tipstanding baffle plates 48a and 48/: (see FIG.5). bolted to webs 46a and 46h respectively. provide means for directingair vertically upwardly for increased contact with speed controlcomponents 2|. The components 2| are conveniently mounted on the outerface of these plates and thus are assured of receiving full cooling airflow on the first pass (see FIG. 5).

As shown in FIG. 5. the baffle plates 48:! and 4811. just described.stop short of the top of cover 26 and thus leave spaces 50:! and 50/1for the turning or transfer of the air flow into the motor at apertures62. Thus. for this streamlined oval design. the upward air flow channel52 is divided by the baffle plates 48a and 48h into front and rearchannels 52a. 52/) above aperture sets 42a and 42/) respectively. and anadditional cham- (ill her 51 is actually formed between baffle plates48a and 48b and the motor housing 54 as shown.

With reference to FIGS. 2. 3 and 5. the motor I4. which includes acylindrical housing 54 and has the coaxial output shaft 16, is mountedvertically in the center of the power unit housing. A radially bladedcentrifugal fan 56 is fixedly keyed to the motor output shaft I6 forpulling air vertically through motor I4 within annular space 87 betweenthe rotor 88 and stator 89 (FIG. 6). which thus forms the second pass ofthe airv As will now be apparent. the provision of air directing means.comprising the webs 46 and flange 78 and the end bell housing (presentlyto be described in detail). enables vertical cooling air flow upwardlythrough the housing 26 and then downwardly through the motor I4 asestablished by the fan 56 and the exhaust in turned and directed throughthe ports 40, as shown in FIG. 5. It is because the intake ports 42 arealso provided in the base of power unit 12, the air has first passedthrough the chambers 52a. 52b where electrical components 21a. 21b. areassured of being cooled completely. Since the motor I4 is run most ofthe time in forward rather than in reverse the blades of fan 56 may beconfigured to be more efficient in the forward direc tion.

Referring to FIG. 2. the motor housing 54 includes top and bottom bellhousings 58 and 60 which respec tively have radial intake and exhaustorifices 62 and 64. The bell housings 58 and 60 are secured preferablyby four anchor rods 68 extending vertically between two groups of fourears 70 and 7l carried by each of the top and bottom bell housings 58and 60. Ears 70 and 7|. which radially extend front cylindrical portions72 and 79. respectively. are preferably equi-angularly spaced about thecylindrical portions. The rods 68 preferably have one end threaded intothe ears 7]. Bolts 73 pass through apertures 75 in the base I5 andthreadably engage the feet 82 on bottont ofears 71 front underneath. Theopposite end of the rods 68 pass through a hole in each ear 7] and arethread-ably engaged by nuts on top ofeach car H and again threadablyengaged by nuts 74 on top of the cover 26. In this manner. all the majorparts of the motor assembly I4 are securely attached together by thefour rods 63. and the cover 26 is also secured. The cover may be removedfrom the power unit by removing nuts 24 and the motor may then beremoved as a unit by simply removing the separate bolts 73.

The end bell housing 60 comprises a generally rectangular flange 78extending from the bottom of cylindrical portion 79. The flange servesas a baffle fitting at its margins against the webs 46a and 46b and thesides 32 ofthe base I5. thereby forming a shroud to isolate the exhaustair being blown through the ports 40. The ears 7] (see FIG. 3) aresufficiently radially spaced outward from the periphery of the fan 56 toprevent any siren like wind noise from developing.

The fan 56 positioned on the shaft I6 is axially aligned with thegenerally annular orifice 64 defined between the flange 78 and a lowercircular baffle structure 80 (see FIG. 3). The underside of structure 80(FIG. 3) includes spaced support feet 82 and a central circular boss 84containing a bushing 86 for the shaft 16. Circular structure 80 is ofsuch a diameter that the exhaust ports 40 extend both radially outwardand inward from the periphery thereof. In this manner. the ports 40 maybe made of full size to accommodate the required air flow. Flow backunder the structure 80 and through annular opening 81 in the end bellhousing 60 (FIG. 3) is important to this feature. The structure 80 notonly defines the final 90 turn in the tortous path of the exhaust airflow (FIG. 5), but also actually forms a mechanical baffle means, bothof which conditions advantageously resist entry of water that might beinadvertantly splashed up from below.

With reference to H65. 2 and 5. particularly. speed control components2|. including SCR control Zla. the details of which does not form a partof the invention per se. but may be of a conventional type. such asGeneral Electric Model 50 having frequency controllable pulse oscillatorand solid state modulating or chopping elements. may be provided. Thecontrol 2111 is advantageously cooled on the first pass of the airthrough the chamber 521: and likewise contactors 21h. 211' are cooled onthe first pass of air through the chamber 52b. The air is nexttransferred through the inner spaces 50a. 5011. and finally passesthrough orifices 62 and down through the annular gap 87 (see FIG. 6)between the rotor 88 and stators 89 for the main cooling operation.

The motor control circuitry includes the battery 20. four groups ofleads )0. 92. 94. 96 interconnecting the components and the motor [4 inany conventional way such that a supply voltage is applied. Thecircuitry pulses the voltage for a fixed period of time. such as 3milliseconds with a controllable repetition rate responsive to thepotentiometer and control switches operated by the twist grip 22.

In the operation of the inventive cooling system. as best depicted inFIG. 5. the centrifugal fan 56 creates a circulating double pass airflow path. Air passes vertically upward into the power unit 12 throughthe screened intake ports 42. over the components 21 within the chamber52 to cool the same. horizontally over the top of the baffle plates 48a.48b. through the transfer spaces 5|). radially into the orifices 62.vertically downward through the annular gap 87 within the motor H tocool both the rotor 88 and the stator 89. radially outward through thecentrifugal fan 56 and annular orifices 64 and turning downwardly andout of the power unit l2 via exhaust ports 40. It should be noted thatthe double pass air flow allows absorbtion of heat from the components2|. as well as radiated heat from the motor H in chamber 52. Then. thereoccurs direct heat transfer in chamber Sl as the air circulates aroundthe motor 14 b v convection and it finally passes through the gap 87within the motor [4 for maximum cooling efficiency. Because of thedouble path flow. a tortuous path is presented for air entering theassembly so that any moisture droplets that might be sucked into theflow. tend to be removed by attachment to an inside wall of the housingprior to reaching the motor 14.

Having thus described a preferred embodiment ofthe present invention andits operation. it should be appar eat that numerous modifications mightbe made to the preferred embodiment within the spirit and scope of thepresent invention. For example. as mentioned briefly above. though notaesthetically desirable because not streamlined. the housing 26 of thepower unit may be provided in a cylindrical configuration and theexhaust air confining means around the end bell housing 60 that isformed by the webs 46a. 46b and the sides 32 of the illustratedembodiment may be one circular wall with the intake ports then extendingaround the full periphery of that wall. Also. the baflle plates 48a. 48band their equivalent in the circular configuration may be omitted. thusallowing the first pass of air to more effectively cool the motor bydirect contact with the outside of the motor housing 54. Furthermore.the principles ofthe invention are quite applicable utilizing apropeller or axial fan in place of the centrifugal fan 56. thusexhausting the air axially directly through holes provided in the endbell housing and base [5. Therefore. it is intended that the descriptionand drawing ofthe preferred embodiment be considered as illustrative ofthe concept of the invention and not in a limiting sense.

What is claimed is:

l. in an electrical outboard motor apparatus including a propeller drivemeans. an air cooled power unit apparatus drivingly positioned abovesaid drive means including an electric motor vertically oriented withina housing. and said motor with an output shaft in driving relationshipto said propeller means. wherein the im provement comprises: a set ofair port means for intake in the bottotn wall of said housing andanother set of air port means for exhaust in the bottom wall of saidhousing; upper and lower orifice means in said motor permitting air flowthrough said motor; said lower orifice means in communication with oneof said sets of air port means. the other of said sets of air port meansbeing located in the bottom wall of the chamber formed by the insidewalls of said housing and the outside walls of said motor: said upperorifice means being in communication with said chamber; a fan mountedupon and driven by the shaft of said motor causing forced aircirculation through said air port means. said orifice means. said motor.and said chamber. thereby providing dual pass cooling air flow. andancillary speed control components necessary for controlling saidelectric motor mounted within said chamber where said speed controlcomponents are cooled by said forced air circulation.

2. The apparatus in claim 1 wherein said fan is a centrifugal fan andsaid exhaust orifice means is annular. said motor having top and bottomend bell housings. said exhaust port means being located at the bottomof said housing to receive the exhaust air from said exhaust orificemeans formed in said bottom end bell housing.

3. The apparatus of claim 2 wherein said bottom end bell housingincludes support ear means spaced radially outward from said fan andspaced horizontal baffle plates supported between said ear means formingsaid annular exhaust orifice means.

4. The apparatus ofclaim 3 wherein said exhaust port means extendradially inward beneath said horizontal baffle plates whereby maximumair flow and tortuous path isolation may be obtained.

5. The apparatus of claim 4 wherein is provided mounting rods passingthrough said power unit housing and interconnecting to the end bellhousings of said motor and to said cover portion.

6. The apparatus of claim l wherein directing means is provided in theform of baffle means extending vertically upward from the bottom of saidhousing and positioned between said intake and exhaust port means.whereby increased air flow over said speed control components isobtained.

7. The apparatus in claim 6 wherein said speed control components aremounted on said baffle means.

1. In an electrical outboard motor apparatus including a propeller drive means, an air cooled power unit apparatus drivingly positioned above said drive means including an electric motor vertically oriented within a housing, and said motor with an output shaft in driving relationship to said propeller means, wherein the improvement comprises: a set of air port means for intake in the bottom wall of said housing and another set of air port means foR exhaust in the bottom wall of said housing; upper and lower orifice means in said motor permitting air flow through said motor; said lower orifice means in communication with one of said sets of air port means; the other of said sets of air port means being located in the bottom wall of the chamber formed by the inside walls of said housing and the outside walls of said motor; said upper orifice means being in communication with said chamber; a fan mounted upon and driven by the shaft of said motor causing forced air circulation through said air port means, said orifice means, said motor, and said chamber, thereby providing dual pass cooling air flow; and ancillary speed control components necessary for controlling said electric motor mounted within said chamber where said speed control components are cooled by said forced air circulation.
 1. In an electrical outboard motor apparatus including a propeller drive means, an air cooled power unit apparatus drivingly positioned above said drive means including an electric motor vertically oriented within a housing, and said motor with an output shaft in driving relationship to said propeller means, wherein the improvement comprises: a set of air port means for intake in the bottom wall of said housing and another set of air port means foR exhaust in the bottom wall of said housing; upper and lower orifice means in said motor permitting air flow through said motor; said lower orifice means in communication with one of said sets of air port means; the other of said sets of air port means being located in the bottom wall of the chamber formed by the inside walls of said housing and the outside walls of said motor; said upper orifice means being in communication with said chamber; a fan mounted upon and driven by the shaft of said motor causing forced air circulation through said air port means, said orifice means, said motor, and said chamber, thereby providing dual pass cooling air flow; and ancillary speed control components necessary for controlling said electric motor mounted within said chamber where said speed control components are cooled by said forced air circulation.
 2. The apparatus in claim 1 wherein said fan is a centrifugal fan and said exhaust orifice means is annular, said motor having top and bottom end bell housings, said exhaust port means being located at the bottom of said housing to receive the exhaust air from said exhaust orifice means formed in said bottom end bell housing.
 3. The apparatus of claim 2 wherein said bottom end bell housing includes support ear means spaced radially outward from said fan and spaced horizontal baffle plates supported between said ear means forming said annular exhaust orifice means.
 4. The apparatus of claim 3 wherein said exhaust port means extend radially inward beneath said horizontal baffle plates whereby maximum air flow and tortuous path isolation may be obtained.
 5. The apparatus of claim 4 wherein is provided mounting rods passing through said power unit housing and interconnecting to the end bell housings of said motor and to said cover portion.
 6. The apparatus of claim 1 wherein directing means is provided in the form of baffle means extending vertically upward from the bottom of said housing and positioned between said intake and exhaust port means, whereby increased air flow over said speed control components is obtained. 